1) The one-time pad (OTP), also known as the Vernam cipher, is a encryption technique that was first described in 1882 and patented in the early 20th century. 2) It works by combining a randomly generated key that is at least as long as the plaintext with the plaintext using an XOR operation. This ensures the ciphertext is random and contains no information about the original message. 3) The key must be truly random, used only once, and both the sender and receiver must destroy their copy after use to maintain the security of the OTP. During the Cold War, spies used small booklets of random numbers as the one-time pads.

1. Network
Security
One time
pad (OTP)/
Verman
cipher

2. Maam Qoseen
Zahra
Uswa Nadeem
3803
Bs(IT)-M
GPCSF

3. One time pad (vernam cipher)
Here’s OTP history :
1. First described by Frank Miller in 1882.The one-time pad was re-invented in 1917 and
patented a couple of years later. It is July 28, 2012 derived from the Vernam cipher,
named after Gilbert Vernam, one of its inventors.
2. One-time use came later, when Joseph Mauborgne recognized that if the key tape were
totally random, then cryptanalysis would be impossible
3. Used by spies of the former USSR (Russia) during the 1960s.
4. Used a stack of small very thin pages, each with a series of random numbers on them.
After use, a page would be destroyed immediately

4. OTP working
Mechanism !
01
The encryption-key has at least the
same length as the plaintext and
consists of truly random numbers
02
An OTP is a list of numbers, in
completely random order, that is used
to encode a message
For example
Plaintext: HEELO
Key: ETQLO
03
This results in a cipher text that has no
relation with the CRYPTO plaintext when
the key is unknown. At the receiving end,
the same OTP is used to retrieve the
original plaintext

5. ● The key is at least as long as the message
● The key is truly random (not auto-
generated)
● Each key should only be used once &
destroyed by CRYPTO sender and
receiver
● There should only be 2 copies of the key
(1 for sender and 1 for receiver)

6. Example OTP :Encryption
keep in mind:
One time pad
fellow the XOR
operation always

7. Example OTP :Decryption

8. Example
Encryption

9. Example
 If the number is negative than +26 is added to make the positive
number (+26-19=7)
Decryption

10. One Time Pads
● Another popular method for distributing
and hiding OTP booklets, was by
printing them at very small size and
hiding them inside common objects like
ballpoints, photo frames and inside a
walnut
● The walnut concealment was very
popular with KGB agents in Western
Europe for many years, until it was
discovered by the West-Germans
Distribution:
• A unique set of OTP booklets needs to be
issued and distributed to each individual spy
or agent abroad.
• As the OTP was destroyed immediately
after use, sufficient and timely supply of
new OTPs had to be guaranteed
Problem with OTPs:
Concealment:

11. Variations
● OTP systems come in many forms and flavors.
The Russian OTP contains only numbers. It
requires the letters of a message to be
converted into numbers, before applying the
OTP.
● An example of such a letter-based OTP It's a
stack of approx. 30 pages that are stapled
together. The cover at the left, contains a
folded alphabet table that is used in the
translation process.
● Some OTPs are so small that they can easily
be hidden inside a small object.

12. Boom Guys, Boom
The End!